PIPDIO24 -1

24-Line High Current Digital I/O PC/104 Module

Description

PIPDIO24-1 (Garnet-MM) is a PC/104-format digital I/O board with 48 lines of I/O. It contains two 82C55 ICs, each having 3 8-bit I/O ports. Each 82C55 has its own 50-pin I/O header for external connections. Direction on all ports is selected by programming control registers built in to the 82C55 chips.

All I/O lines are buffered with transceivers, whose directions are controlled by logic which responds to the direction control values written to the 82C55s. Each line is capable of sourcing 35mA in a logic low state or sinking 6mA in a logic high state. The board is constructed entirely with CMOS logic to reduce power consumption and requires only +5V for operation.

PIPDIO24-1's I/O headers are organized to allow direct interfacing to OPTO-22's isolated I/O racks, including the G4 series, the PB16-H, -J, -K, -L, PB8H, and the PB24HQ. These racks and I/O modules allow up to 3000 VRMS isolation between the computer and the user's signals. All control signals, power, and ground on the PIPDIO24-1 I/O header match the corresponding signals on these I/O racks, so a single 50-pin ribbon cable, such as Diamond Systems' C50-3, is all that is needed to make the connection.

The board provides access to interrupt levels 2-7 on the PC bus for real-time background applications. Interrupts can be generated in two ways. In Mode 0 operation, a rising edge on one of four interrupt lines causes the board to generate an interrupt request on the bus. In Mode 1 operation, the 82C55 generates interrupts in response to handshake signals between PIPDIO24-1 and external circuitry.

Software drivers are included with PIPDIO24-1 to allow controlling the board from Microsoft C, QuickC, GW-Basic, and QuickBasic languages. The software driver supports all of the board's features, including interrupt operation. Example programs demonstrate the use of the function calls and provide a starting point for program development.

High-Current Capability for Solid State Relays

PIPDIO24-1 was specifically designed for applications that use mechanical or solid state relays, such as the OPTO22 G4 series. These devices typically require more drive current than many digital I/O cards can supply. For example, an OPTO22 output module requires 12mA of drive current, whereas a typical 82C55-based digital I/O card can only supply 2.5mA. However, all output lines on PIPDIO24-1 have high-current buffers capable of driving up to 64mA each when low and 15mA each when high. This is enough for solid state relays and many mechanical relays as well. These output buffers change direction automatically in response to the direction control bytes written to the board. In addition, power and ground for the rack are provided straight from the board's I/O header, along with the data lines needed to read from and write to the relays.

Specifications

Information contained in this document is subject to change without notice.
Other products and companies referred to herein are trademarks or registered trademarks of their respective companies or mark holders.